Minimally invasive surgical (MIS) instruments are often preferred over traditional open surgical devices due to the reduced post-operative recovery time and minimal scarring associated with minimally invasive procedures. Laparoscopic surgery is one type of MIS procedure in which one or more small incisions are formed in the abdomen and a trocar is inserted through the incision to form a pathway that provides access to the abdominal cavity. The trocar is used to introduce various instruments and tools into the abdominal cavity, as well as to provide insufflation to elevate the abdominal wall above the organs. Endoscopic surgery is another type of MIS procedure in which elongate flexible shafts are introduced into the body through a natural orifice.
Due to the benefits associated with minimally invasive surgeries, significant efforts have gone into developing a range of endoscopic and laparoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
For example, end effectors for grasping tissue have been developed which secure tissue between two jaws. Though two-jawed graspers can be effective to engage tissue therebetween, graspers must exert significant compressive forces on the target tissue in order to insure a firm grasp. Due to the constraints of operating in confined spaces, however, graspers must often utilize relatively small tissue-engaging surfaces which decrease the tissue area to which the force is applied, thereby leading to increased risk of unintentional tissue damage. Merely increasing the size of the grasper is impractical, however, as such efforts are limited by the size of the access port and the surgeon's need to visualize the surgical site and/or deliver multiple end effectors thereto. Further, the limited range of motion of the two-jawed graspers can make it difficult to occlude a puncture site, for example, as the two jaws must be precisely aligned with target tissue site to ensure capture. Similarly, two-jawed end effectors for dissecting (e.g., separating or spreading) tissue can lead to unintentional tissue damage tissue due to the pressure placed on the tissue by the two jaws, while possibly limiting the access due to the end effector's lack of freedom of movement. For example, conventional two-jawed dissectors typically generate an elongate access slot in the dissected tissue.
Accordingly, there remains a need for improved end effectors and methods of operating the same, and in particular to methods and devices for grasping or dissecting tissue.